Transcript for Jim Foley's Brother Says the US Could Have Done More to Save His Brother's Life

And now, the other big story of the day. James Foley, killed by terrorist terrorists. And his family now speaking out, did the United States do enough to safe him? And the U.S. Launches a new round of attacks on the ruthless, implaquable force. Jonath Jonathan Karl now. The United States could have done more on behalf of the western and American hostages over there. And still, you know, dealt with the broader worldwide issues. Reporter: Foley said the U.S. Could have considered a prisoner exchange. But today, the white house said it did all it could. I assure you that we have done everything that we can possibly do to try to bring home our hostages. Tragically, we weren't able to rescue Mr. Foley, but we're going to keep trying for all of our hostages. Reporter: Also today, Foley's parents revealed the last e-mail they received from the terrorists, just ten days ago. Still some hope that he would be freed. "You don't spare our weak, elderly, or children, so we will not spare yours." U.s. Officials tell ABC news the group is holding at least three more Americans. And the U.S. Is keeping up the pressure on the group. Targets near Iraq's mosul dam. And more air strikes coming in the next 14 days. And the white house absolutely considers the killing of Foley a terrorist attack. One official said today, we're not going to be restricted by borders. And as you well know, another warning about Isis sympathizers in the U.S. Pierre Thomas has that. Reporter: Well, today a bulletin to police across the country, warning to look out for Isis sympathizers here. Sources say there's clearly a pool of people in the U.S. That identify with these radicals. Today's bulletin targets sympathizers in the shadows that may not be known to police. No specific threat has been identified, but they're wild

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